Method and apparatus for removing pre-placed prosthetic joints and preparing for their replacement

Abstract

A method and apparatus for removing a pre-placed prosthetic joint from a bone cavity and conditioning the cavity for receipt of a replacement joint. The pre-placed joint is first pulled from the mantle of hardened cement holding it within the cavity, thus leaving a cavity within the mantle. A mass of fluid cement is then placed within the cement cavity, after which a pulling appliance is inserted into the fluid cement and the fluid cement is permitted to cure to bond the appliance to the mantle. Tension is then applied to the pulling appliance to remove the appliance and the cement mantle from the bone cavity as a unit. The fluid cement partially dissolves and softens the hardened cement mantle so that an integral cement mass is formed upon curing of the fluid cement. The pulling appliance is of a screw-like configuration, with means to connect a slap-hammer to its proximal end.

I claim: 
     
       1. A method for removing a prosthetic appliance secured in place by a mantle of hardened methylmethacrylate cement received within a bone cavity and conditioning the bone cavity for receipt of a new appliance, said method comprising: (a) pulling the appliance from the mantle of hardened cement to leave a cement cavity within the mantle;   (b) injecting a fluid mass of methylmethacrylate cement into the cement cavity;   (c) inserting a post having an irregular exterior surface into the fluid mass of methtylemethacrylate cement;   (d) permitting said fluid mass of methylemethacrylate cement to harden and bond to the post and the hardened mantle; and,   (e) applying tension to the post to pull the post and the bonded mantle of methylemethacrylate cement from the bone cavity.   
     
     
       2. A method according to claim 1 further comprising abrading and cleaning the cement cavity prior to injecting the fluid mass of methylemethacrylate cement into said cavity. 
     
     
       3. A method according to claim 2 further comprising: (a) measuring the depth of the cement cavity prior to inserting the post into the mass of fluid cement; and,   (b) controlling the depth to which the post is inserted into the cement cavity so that the penetration of the post into the cement cavity does not exceed the depth thereof.   
     
     
       4. A method according to claim 1 wherein the step of injecting the fluid mass of cement into the cement cavity comprises: (a) placing a cap over the open end of the cement cavity;   (b) extending a nozzle through the cap to the bottom of the cement cavity;   (c) forcing fluid cement into the bottom of the cement cavity through the nozzle while venting air from the top of the cement cavity until the cavity is substantially full of said fluid cement; and,   (d) withdrawing the nozzle from the cement cavity while continuing to force fluid cement through the nozzle to fill the cement cavity with a void free mass of fluid cement.   
     
     
       5. A method according to claim 4 wherein the post is inserted into the fluid mass of cement through the cap. 
     
     
       6. A method according to claim 1 wherein: (a) the post is generally rectilinear and the irregular surface thereof comprises helical threads; and,   (b) the post is inserted into the mass of fluid cement by turning the post about its longitudinal axis to screw the threads into the fluid cement.   
     
     
       7. A method according to claim 6 wherein: (a) the post has a distal end and a tapered section which converges toward a distal end;   (b) the threads are formed on the tapered section; and,   (c) the post is screwed into the fluid cement distal end first.   
     
     
       8. A method according to claim 7 wherein the distal end of the post comprises a section of reduced diameter extending from the tapered section. 
     
     
       9. A method according to claim 1 wherein tension is applied to the post by securing a slap-hammer to the post and subjecting the post to impact tension through the slap-hammer. 
     
     
       10. A method according to claim 9 wherein the post is rectilinear and the impact tension is applied in generally axial alignment relative thereto. 
     
     
       11. A method for removing a hardened mantle of methylemethacrylate cement adhered to a bone, said method comprising: (a) placing a mass of fluid methylemethacrylate cement in intimate contact with the hardened mantle of cement to at least partially dissolve and soften the hardened mantle;   (b) imbedding a pulling appliance within the fluid cement;   (c) permitting the fluid mantle of cement and softened mantle to cure and bond together; and,   (d) applying tension to the pulling appliance to pull the appliance and the bonded mantle from the bone.   
     
     
       12. A method according to claim 11, wherein: (a) a cavity is formed in the hardened mantle prior to placing the fluid mass of cement;   (b) the fluid mass of cement is placed within the cavity formed in the mantle; and,   (c) the pulling appliance is imbedded in the fluid mass of cement so as to extent into the cavity formed in the mantle.   
     
     
       13. A method for removing a pre-placed prosthetic hip joint secured in place within a bone cavity in the end of the femur adjacent the torchanter by a mantle of hardened cement and conditioning the bone cavity for receipt of a new joint, said method comprising: (a) pulling the pre-placed joint from the mantle of hardened cement to leave a cement cavity within the mantle;   (b) injecting a mass of fluid cement into the cement cavity;   (c) inserting a post having an irregular exterior surface into the mass of fluid cement;   (d) permitting said mass of fluid cement to harden and bond to the post and the hardened mantle; and,   (e) applying tension to the post to pull the post and the bonded mantle of cement from the bone cavity.   
     
     
       14. A method according to claim 13 further comprising cutting the trochanter off of the femur to expose the hardened mantle within the bone cavity prior to pulling the pre-placed joint from the mantle. 
     
     
       15. A method according to claim 13 further comprising abrading and cleaning the cement cavity prior to injecting the mass of fluid cement into said cavity. 
     
     
       16. A method according to claim 15 further comprising: (a) measuring the depth of the cement cavity prior to inserting the post into the mass of fluid cement; and,   (b) controlling the depth to which the post is inserted into the cement cavity so that the penetration of the post into the cement cavity does not exceed the depth thereof.   
     
     
       17. A method according to claim 13 wherein the step of injecting the mass of fluid cement into the cement cavity comprises: (a) placing a cap over the open end of the cement cavity;   (b) extending a nozzle through the cap to the bottom of the cement cavity;   (c) forcing fluid cement into the bottom of the cement cavity through the nozzle while venting air from the top of the cement cavity until the cavity is substantially full of said fluid cement; and,   (d) withdrawing the nozzle from the cement cavity while continuing to force fluid cement through the nozzle to fill the cement cavity with a void free mass of fluid cement.   
     
     
       18. A method according to claim 17 wherein the post is inserted into the mass of fluid cement through the cap. 
     
     
       19. A method according to claim 13 wherein: (a) the post is generally rectilinear and the irregular exterior surface thereof comprises helical threads; and,   (b) the post is inserted into the mass of fluid cement by turning the post about its longitudinal axis to screw the threads into the fluid cement.   
     
     
       20. A method according to claim 19 wherein: (a) the post has a distal end and a tapered section which converges toward distal end;   (b) the threads are formed on the tapered section; and,   (c) the post is screwed into the fluid cement distal end first.   
     
     
       21. A method according to claim 20 wherein the distal end of the post comprises a section of reduced diameter extending from the tapered section. 
     
     
       22. A method according to claim 13 wherein tension is applied to the post by securing a slap-hammer to the post and subjecting the post to impact tension through the slap-hammer. 
     
     
       23. A method according to claim 22 wherein the post is rectilinear and the impact tension is applied in generally axial alignment relative thereto.